The technical solution which forms the subject matter of this disclosure was initially developed with reference to the sector of simultaneous thawing of a plurality of deep-frozen food products, but it may advantageously be applied in general for heating food products for any purpose. However, for simplicity, hereinafter reference will mainly be made to the thawing sector.
In the catering sector, in particular in that of fast food, some food products, to be used for preparing various foods, are initially available deep-frozen and a predetermined quantity of them is thawed in advance on a daily basis so that it is available when required.
Whilst the deep-frozen products awaiting use are preserved in suitable cold storage rooms able to preserve them at relatively low temperatures (approximately at least −18° C.), those that must be thawed daily are usually taken out of the cold storage rooms a day early and are placed in suitable thawing apparatuses.
In large catering restaurant chains, where the entire procedure is highly standardized, the deep-frozen food products are supplied to each point of sale packaged in packages having practically constant dimensions and weight. For example, hamburgers may be packaged in packages containing several dozen pieces stacked and positioned side by side in such a way as to constitute an almost parallelepiped block. Therefore, in large fast food restaurant chains, on a daily basis the point of sale thaws a predetermined number of blocks of hamburgers, in order to meet the foreseeable customer demand.
According to the most widespread prior art in catering, the thawing of food products is carried out in suitable apparatuses, appropriately designed for that purpose. In the most widespread embodiments, such apparatuses are substantially refrigerators combined with a generator of air at a controlled temperature (normally between 0° C. and 20/25° C.) which have a plurality of housing compartments in which the deep-frozen food products can be inserted. The actual thawing is performed by circulating air at a controlled temperature (a temperature that generally at the start is equal to 20/25° C. and that is gradually reduced to approximately 0/2° C. during the process). Once thawing is complete or almost complete, a refrigerating circuit begins operating, designed to preserve the foods at a temperature of approximately 0/2° C. Generally, such apparatuses are able to thaw food products over a period of many hours (in many cases just under twenty-four hours), therefore, every day the point of sale must empty the thawed products from the apparatus (which are then advantageously preserved in normal refrigerators until they are used) and load the apparatuses with new products to be thawed.
In the case of deep-frozen food products with standardized packaging, it is also generally the case that, to minimize overall dimensions, each housing compartment of the prior art apparatuses has a volume that is made to measure for the block to be thawed, that is to say, slightly larger than that of the block.
It is easy to see how this technology has considerable limits and may therefore cause significant disadvantages.
In particular, the thawing times are long and make dynamic management of the food products depending on the actual customer demand impossible. Each point of sale must plan one day, how many food products it must thaw for the next day. If demand is overestimated, at the end of the following day the point of sale will have to dispose of the excess products as rubbish. If, on the other hand, the demand is underestimated, at a certain point during the following day, the point of sale will be unable to meet customer demand.
Faced with these issues, points of sale would generally prefer to overestimate demand, with the consequent risk of wasting a predetermined number of food products, rather than risk disappointing the customers.
There are also known, at least at a documented level (see for example U.S. Pat. No. 4,296,299 or JP H05 41971), apparatuses for thawing food that use radio frequency dielectric heating, and that have the theoretical advantage of allowing heat generation inside the deep-frozen food products, with a consequent improvement as regards thawing times. However, such apparatuses have not yet actually spread much at a commercial level, probably due to the technical difficulties involved, especially as regards the need to thaw the food products without running the risk of locally cooking them and the difficulty in obtaining good efficiency (in fact, there is a real risk that even 90% of the energy consumed will be dissipated in the form of heat in the electromagnetic field generator, rather than in the products to be thawed). Moreover, all of the prior art solutions of this type deal exclusively with the subject of thawing a single product (or block of products), and not that of thawing multiple products, as is required in the catering sector.
In this context, there is a real need to produce an apparatus for simultaneously heating a plurality of food products which overcomes the above-mentioned disadvantages.
In particular, there is the need to produce an apparatus for simultaneously heating a plurality of food products that allows the products to be thawed more rapidly than the prior art apparatuses.
Furthermore, there is the need to produce an apparatus for simultaneously heating a plurality of food products that allows the products to be thawed in a controlled way, that is to say, avoiding excessively overheating them even in the case of particularly rapid thawing operations.
Moreover, the need is felt to produce an apparatus for simultaneously heating a plurality of food products that has a relatively high level of efficiency.